** Description changed: I'm using Ubuntu 13.04 dev and have noticed a high cpu overhead if a - process is using multiple threads and computing them on different - threads. To measure this I have written a little script in Python which - I will attach. + process is using multiple threads and computing them on different cores. + To measure this I have written a little script in Python which I will + attach. The script will create 2 threads which are using only a little time of a cpu core. On my AMD Phenom II X6 1045T the Linux kernel will assign the 2 threads on 2 cores which will use a total cpu time of 40% from a maximum of 600%. But if I'm using "taskset -ap 0x00000001 pid_of_script" the 2 threads will be assigned to 1 core and the total cpu usage will be only 25% from 600%. I'm wondering why there is a cpu overhead of 60% if the Linux kernel is using 2 cores instead of 1 core. - --- + --- AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.25. AplayDevices: - **** List of PLAYBACK Hardware Devices **** - card 0: SB [HDA ATI SB], device 0: ALC662 rev1 Analog [ALC662 rev1 Analog] - Subdevices: 0/1 - Subdevice #0: subdevice #0 + **** List of PLAYBACK Hardware Devices **** + card 0: SB [HDA ATI SB], device 0: ALC662 rev1 Analog [ALC662 rev1 Analog] + Subdevices: 0/1 + Subdevice #0: subdevice #0 ApportVersion: 2.6.1-0ubuntu6 Architecture: amd64 AudioDevicesInUse: - USER PID ACCESS COMMAND - /dev/snd/controlC0: sworddragon 2374 F.... plugin-containe - /dev/snd/pcmC0D0p: sworddragon 2374 F...m plugin-containe - /dev/snd/timer: sworddragon 2374 f.... plugin-containe + USER PID ACCESS COMMAND + /dev/snd/controlC0: sworddragon 2374 F.... plugin-containe + /dev/snd/pcmC0D0p: sworddragon 2374 F...m plugin-containe + /dev/snd/timer: sworddragon 2374 f.... plugin-containe CRDA: Error: [Errno 2] No such file or directory Card0.Amixer.info: - Card hw:0 'SB'/'HDA ATI SB at 0xf9ff4000 irq 16' - Mixer name : 'Realtek ALC662 rev1' - Components : 'HDA:10ec0662,18497662,00100101' - Controls : 33 - Simple ctrls : 18 + Card hw:0 'SB'/'HDA ATI SB at 0xf9ff4000 irq 16' + Mixer name : 'Realtek ALC662 rev1' + Components : 'HDA:10ec0662,18497662,00100101' + Controls : 33 + Simple ctrls : 18 CurrentDmesg: - Error: command ['sh', '-c', 'dmesg | comm -13 --nocheck-order /var/log/dmesg -'] failed with exit code 1: comm: /var/log/dmesg: No such file or directory - dmesg: write failed: Broken pipe + Error: command ['sh', '-c', 'dmesg | comm -13 --nocheck-order /var/log/dmesg -'] failed with exit code 1: comm: /var/log/dmesg: No such file or directory + dmesg: write failed: Broken pipe DistroRelease: Ubuntu 13.04 EcryptfsInUse: Yes IwConfig: Error: [Errno 2] No such file or directory Lsusb: Error: [Errno 2] No such file or directory MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M. MarkForUpload: True NonfreeKernelModules: nvidia Package: linux (not installed) ProcEnviron: - TERM=xterm - PATH=(custom, no user) - LANG=de_DE.UTF-8 - SHELL=/bin/bash + TERM=xterm + PATH=(custom, no user) + LANG=de_DE.UTF-8 + SHELL=/bin/bash ProcFB: 0 VESA VGA ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-17-generic root=UUID=f1ce7323-74dc-46f7-95f7-887cc54403e7 ro ProcVersionSignature: Ubuntu 3.5.0-17.28-generic 3.5.5 RfKill: Error: [Errno 2] No such file or directory Tags: raring Uname: Linux 3.5.0-17-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: adm cdrom dialout lpadmin plugdev sambashare sudo dmi.bios.date: 05/21/2012 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: P1.20 dmi.board.asset.tag: BC5FF4739C55 dmi.board.name: 960GM/U3S3 FX dmi.board.vendor: ASRock dmi.chassis.asset.tag: To Be Filled By O.E.M. dmi.chassis.type: 3 dmi.chassis.vendor: To Be Filled By O.E.M. dmi.chassis.version: To Be Filled By O.E.M. dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.20:bd05/21/2012:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rn960GM/U3S3FX:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.: dmi.product.name: To Be Filled By O.E.M. dmi.product.version: To Be Filled By O.E.M. dmi.sys.vendor: To Be Filled By O.E.M.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1073148 Title: High cpu overhead on using multiple cores To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1073148/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
